Pulse-generating circuit



Feb. 14, 1961 R. L. WATTERS 2, 7

PULSE-GENERATING CIRCUIT Original Filed April 21, 1953 Mumwakarak INVENTOR. Roamr L. WflTTE/CS HTTORNEYS United States Patent PULSE-GENERATING CIRCUIT Robert L. Watters, Schenectady, N.Y., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Continuation of abandoned application Ser. No. 350,007, Apr. 21, 1953. This application May 22, 1958, Ser- No. 737,181

4 Claims. (Cl. 328-35) This application is a continuation of my application Serial No. 350,007, filed April 21, 1953, now abandoned, and relates to pulse-generating circuits and morevparticularly to a circuit for producing a pulse having a variable slope on its leading edge and a sharp cut-ofi on its trailing edge.

in special systems, such as television and radar, and in highly complex electronic accelerating equipment, such as synchrotrons, it is sometimes desirable that the envelope 5 the radio-frequency accelerating voltage have a particular wave shape. ()ne object of the invention is to provide a pulse-generating circuit for producing a pulse having a variable slope on its leading edge.

Another object of the invention is to provide in a pulsegenerating circuit means for varying the slope of the leading edge of a pulse produced by such circuit.

A further object of the present invention is to generate electrical pulses having a variable slope on the leading edge and a sharp cut-oft on the trailing edge.

The invention will best be understood from the following description of a specific embodiment when read in conjunction with the accompanying drawing.

In the drawing, the pulse-generating cricuit consists of a standard multivibrator 1 in series with the cathode of a five-electrode tube 3 having an anode 5, a cathode 7, a control grid 9, a screen grid 11 and a suppressor grid 13, said elements being connected as shown. A series resistance-capacitance network consisting of a variable resistor 15 and capacitor 17 is connected between the plate 5 of tube 3 and ground. Control grid 9 is connected between condenser 17 and resistor 15. A condenser 19 is inserted between said grid 9 and resistor 15 and between multivibrator 1 and cathode 7. A resistor 18 is connected across the output circuit of multivibrator 1. Suppressor grid 13 is connected to cathode 7 and serves to prevent the passing of secondary electrons from anode 5 and creen grid 11. Blocking condenser 21 is connected between screen grid 11 and ground.

In series with plate 5 and suppressor grid 11 are two resistors 23 and 25 respectively, said resistors providing plate and screen potentials to tube 3. The output circuit is taken between anode 5 and ground and is terminated at terminals 27 and 29.

In operation, an essentially negative square-wave output voltage 31 of multivibrator 1 is fed to tube 3 to initiate conduction. When current flows from multivibrator 1 through resistor 18 the current in pentode 3 is cut oil. As the leading edge of pulse 31 extends in a negative direction, plate current will start to flow in tube 3 causing the plate voltage to drop. A portion of the plate voltage is fed back to grid 9 through condenser 17 and presents a sudden change in current flow through the tube. When the pulse 31 returns to its original state the pentode is again driven to cut-0E. Condenser 19 tends to minimize a small transient that is developed as a result of the feedback circuit.

The length of time that the output 33, or radioirequency accelerating voltage, is on is determined by the 2,972,110 Patented Feb. 14, 1961 constant of condenser 17 and resistor 15 and the DC.

gain of tube 3. Because resistor 15 is variable, pulse 33 generated by tube 3 has a leading edge that is variable. The trialing edge of the generated pulse is always sharp because multivibrator 1 cuts ed the plate current in tube 3 so so that control grid 9 has no efiect on that part of the cycle.

The invention is not to be construed as limited to the particular circuit for generating a pulse having a variable slope on the leading edge and a sharp trailing edge as described herein, since this is regarded to be illustrative rather than restrictive.

What is claimed:

1.'A circuit for generating an output pulse having a sloping leading edge and a sharp trailing edge, said circuit comprising means producing a substantially rectangular control impulse, the leading edge of which extends in a negative direction, a pentode having a plate, a suppressor grid, a screen grid, a control grid and a cathode, circuit means connected to said plate, cathode, suppressor and screen grids adapted to impress conduction potentials on the elements of said pentode when a supply potential referenced to ground is applied to said circuit means, means for applying said rectangular control impulse output to the cathode of said pentode to initiate the conduction thereof on the leading edge of such control impulse, and to terminate conduction on the trailing edge, a series resistance-capacitance network connected in parallel with the plate circuit of said pentode, said series network being connected between the plate of said pentode and ground, the plate being connected to the capacitor and the control grid of said pentode being joined to a point between the resistor and capacitor of said network, the other end of said resistor being connected directly to ground, the rate of current increase through the tube being dependent in part upon the time constant of said series network, said resistor of the series network being variable to vary the time constantof said network and hence the slope of the leading edge or" said output pulse, and means for deriving said output pulse from the plate of said pentode.

2. In combination with means producing a substantially rectangular control impulse the leading edge of which extends in a negative direction, a five-electrode tube having a plate, a suppressor grid, a screen grid, a control grid and a cathode, circuit means connected to said plate, cathode, suppressor and screen grids adapted to impress conduction potentials on the elements of said pentode when a supply potential referenced to ground is applied to said circuit means, means for applying said rectangular control implse output to the cathode of said five-electrode tube to initiate the conduction thereof on the leading edge of such control impulse and to terminate conduction on the trailing edge, and a series resistance-capacitance network connected in parallel with the plate circuit of said five-electrode tube, the plate being connected to one side of the capacitor, the control grid being connected to the resistance-capacitance junction, and the other side of the resistance being connected directly to ground, the current increase through the tube being dependent in part upon the time constant of said series network.

3. A circuit for generating an output pulse having a sloping leading edge and a sharp trailing edge comprising: connections for a source of substantially rectangular pulses the leading edges of which extend in a negative direction; a unidirectional current device having an emitting element, a control element and a collecting element; circuit means connected to said current device adapted to impress conduction potentials 'on the elements of said device when a supply potential referenced to ground is ap plied to said circuit means; means connected to said pulsesource connections applying said rectangular pulses to the emitting element circuit of said current device to initiate conduction therein on the leading edge or each 7 said rectangular pulse and to terminate conduction on the trailing edge; a series resistance-capacitance network connected in parallel with the emitting element-collecting element circuit of said current device, the capacitance end of said network being connected to said collecting element and said control element being connected to the junction of said resistance and said capacitance, the resistance end of said network being connected directly to ground, the rate of current increase through said current device being dependent in part upon the time constant of said resistance-capacitance network; and means deriving said output pulse from the emitting element-collecting element circuit of said device.

4. A circuit for generating an output pulse having a variable slope leading edge and a sharp trailing edge comprising a circuit as set forth in claim 3, wherein said resistance of said resistance-capacitance network is a variable resistance.

OTHER REFERENCES Article entitled Design of Phantastron Time Delay Circuits, by Close and Lebenoaum, Electronics, April 1948, Pp. 100-107. 

